Vehicular cement mixers are known (e.g. German open application Ser. No. 2,139,492) in which a hydrostatic motor driven by the vehicle engine via a power pump rotates a mixing drum via a mechanical transmission. An ancillary transmission is necessary to drive a fan for cooling the pumping oil.
Conventional cement-mixer drive systems have various disadvantages. For example, the housing space that the hydrostatic motor requires is frequently used for other elements, and the noise produced by the motor cannot be lessened. Furthermore, the bulkiness of the heat exchanger and the oil reservoir necessitates extensive hose connections between the motor and the heat exchanger and between the exchanger and the oil reservoir. The transmission driving the cooling fan must also be provided with a step-down power train.